3 ms·

True, I've gotten Pi 4s pretty low (< 1W), disabling the LEDs, Ethernet, HDMI, and USB controller, but it's never gonna equal a proper suspend.

Fnoord 3y ago
How did you disable the LED? I mean I can disable LEDs via /proc but not in config.txt correct?
- pja 3y ago
  Add # Disable Power LED after boot dtparam=pwr_led_activelow=off # Disable SD card activity led dtparam=act_led_trigger=none dtparam=act_led_activelow=off # Disable the ethernet LEDs - these are Pi4 specific values. # Look in the docs for the values for other Pi boards. dtparam=eth_led0=4 dtparam=eth_led1=4 to /boot/config.txt
  - Fnoord 3y ago
    Thank you! It appears to depend on firmware or kernel but for recent kernels (recent 6.1 or 6.2) activelow is no longer necessary [1]. It seems to work on CM4. PS: my bad I disabled the LEDs via /sys not /proc previously: > # for i in /sys/class/leds/*; do echo 0 > "$i/brightness"; done [1] https://github.com/raspberrypi/firmware/issues/1742 https://github.com/raspberrypi/firmware/issues/1742
    - doubled112 3y ago
      I've had this drive me crazy. The required lines were different between the Pi 2 and Pi 4 I was using at the time, and the documentation was not updated (or I'd found old docs). An exercise in trial and error.
sapiogram 3y ago
1W is honestly not that great, though. A smartphone will do 10x that out of the box, and still pling for Facebook notifications.
- nine_k 3y ago
  A smartphone has two entirely separate computers in it, the one that runs Android or iOS, and the baseband controller. The latter is built to be very power-efficient while waiting for a radio signal. It will wake up the dormant application OS computer when a push notification comes in. The same likely can be built on top of an RPi, using, say, wake-on-LAN signaling, or some GPIO as an interrupt source. You'll have to suspend your OS while idle for a prolonged time though.

Fnoord 3y ago

How did you disable the LED? I mean I can disable LEDs via /proc but not in config.txt correct?

pja 3y ago
Add # Disable Power LED after boot dtparam=pwr_led_activelow=off # Disable SD card activity led dtparam=act_led_trigger=none dtparam=act_led_activelow=off # Disable the ethernet LEDs - these are Pi4 specific values. # Look in the docs for the values for other Pi boards. dtparam=eth_led0=4 dtparam=eth_led1=4 to /boot/config.txt
- Fnoord 3y ago
  Thank you! It appears to depend on firmware or kernel but for recent kernels (recent 6.1 or 6.2) activelow is no longer necessary [1]. It seems to work on CM4. PS: my bad I disabled the LEDs via /sys not /proc previously: > # for i in /sys/class/leds/*; do echo 0 > "$i/brightness"; done [1] https://github.com/raspberrypi/firmware/issues/1742 https://github.com/raspberrypi/firmware/issues/1742
  - doubled112 3y ago
    I've had this drive me crazy. The required lines were different between the Pi 2 and Pi 4 I was using at the time, and the documentation was not updated (or I'd found old docs). An exercise in trial and error.

sapiogram 3y ago

1W is honestly not that great, though. A smartphone will do 10x that out of the box, and still pling for Facebook notifications.

nine_k 3y ago
A smartphone has two entirely separate computers in it, the one that runs Android or iOS, and the baseband controller. The latter is built to be very power-efficient while waiting for a radio signal. It will wake up the dormant application OS computer when a push notification comes in. The same likely can be built on top of an RPi, using, say, wake-on-LAN signaling, or some GPIO as an interrupt source. You'll have to suspend your OS while idle for a prolonged time though.